In a system of purified components , the affinity of binding of a DNA fragment containing a FXRE from __SP__ __NODE__ gene and a protein protein complex consisting of __SP__ __NODE__ and of __SP__ __NODE__ is greater than the affinity of binding of a DNA fragment containing a FXRE from __SP__ __NODE__ gene and a protein protein complex consisting of __SP__ __NODE__ and of __SP__ __NODE__ .